THE Brighton bombing assassination attempt on Margaret Thatcher and her Cabinet led to the near-total collapse of secret Northern Ireland peace talks, official documents reveal today.

Mrs Thatcher and husband Denis on the night of the 1984 bomb. [EXPRESS NEWSPAPERS]

The IRA’s attack on the Grand Hotel during the Tory party conference on October 12, 1984, killed five people, including MP Anthony Berry.

Another 31 were injured, including Lord Tebbit and his wife Margaret.

Four months earlier the then Prime Minister had secured Cabinet approval for secret negotiations with the Irish government, it is revealed as papers are released under the 30-year rule.

The “Armstrong/Nally talks” were named after Sir Robert Armstrong, then Cabinet secretary, and his Irish government counterpart Dermot Nally.

The talks have since been hailed as crucial to the 1985 Anglo-Irish Agreement.

But documents revealed today show that Mrs Thatcher was reluctant to go on with the negotiations after Brighton.

In scrawled writing on one communication with advisers in the following week, she wrote: “I’m very pessimistic.

“I do NOT think we can take this matter much further.”

Before IRA terrorist Patrick Magee’s blast threatened the peace talks, they had been successful at that point.

In a briefing paper drafted in the week before the bomb – published for the first time today – Sir Robert outlined proposals for a joint security commission, mixed law courts and possibly an Anglo-Irish parliament.

The scene of devastation at the Grand Hotel in Brighton [PA]

I do NOT think we can take this matter much further

Margaret Thatcher

He wrote in addition: “Both sides agree that it would be desirable to introduce a system of devolved government into Northern Ireland.”

But Mrs Thatcher’s correspondence revealed in the National Archives today, make it clear she tried to cool negotiations after the bomb.

In a handwritten note, she told Charles Powell, one of her closest advisers: “The bomb has slowed things down and may in the end kill any new initiative because I suspect it’s the first in a series.”

On the same day, Mrs Thatcher added: “The events of Thursday night in Brighton mean that we must go very slowly on these talks, if not stop them.

“It could look as if we were bombed into making concessions to the Republic.”

Mr Powell wrote to Sir Robert, clarifying: “The PM does not at this stage wish you to discuss a possible communique for the Anglo-Irish summit with Irish officials.

“She wishes to reflect further on whether there should be a communique at all.”